Some countries like Singapore, Hong Kong and the PRC spits strictly prohibited by law. But still in the country with the implementation of Singapore's top law though, still there is one creature that was not banned spitting, even advisable because it can increase national income. So precious creatures who spit it none other than the swallow bird, the other is a bird called a kite and in English is called Swallow. With thick saliva swiftlet makes its nest. Thick saliva that dries when exposed to air. Nowadays in the world known two types of swallow nest swiftlet nests which are harvested in the caves in the mountains, as well as swallow nest on the roof of the harvesting of old houses is more popular as a nest swiftlet home.

Bird Nests are insectivorous birds which are aerial and likes to slide. This dark-colored birds, flying faster with body size medium / small, and has a narrow crescent-shaped wings and a pointed, very small feet and so did the beak of this bird species has never perched in a tree. Swiftlet in the habit of living in the caves or houses are quite humid, dimly lit until dark and use ceilings to attach the nest as a place to rest and breed.

Swiftlet classification is as follows:
Superorder: Apomorphae
Order: Apodiformes
Family: Apodidae
Sub Family: Apodenae
Tribes: Collacaliini
Genera: Collacalia
Species: Collacaliafuciphaga

Swiftlet makes its nest on the roof of the old houses usually have been cultivated by families or companies that do business like this since long. Because of its natural and rare (Many swiftlet nest harvesters who met his end of each year when the harvest in the cave) the selling price of a cave swallow nest is far more expensive than homemade swallow nest. In the market, also known term swallow nest clean and dirty. The net is a swallow bird's nest that has been washed and cleaned and ready to be cooked.

Swiftlet nests are generally easily available in the market or drug store in Chinatown. Usually sold in containers or kiloan. In restaurants swiftlet nests are usually presented in the form of soups or sweets for dessert. Yan Wo so his name is pronounced in Mandarin, has for centuries made the upscale food.

High nutrient content which makes it is believed to have aphrodisiac properties as that in a certain period can only be enjoyed by the nobility in ancient China. Many sinshes and expert blending of traditional China medicine swallow nest into the tonic amplifier. Later swallow bird's nest soup is packaged and produced in a modern way as one tonic energy enhancer. Unfortunately the price is very expensive, so even though the modern era and the nobility was no longer monopolize every aspect of this earth, swallow nest is still not affordable by everyone